This invention relates to the improved manufacture of preparations rich in interferon. Interferon is a protein synthesized by cells in response to induction by viruses or other substances. To date, sufficient clinical evidence of the potential therapeutic value of interferon has been gathered to generate some optimism that interferon may become an important antiviral and/or anti-tumor agent. Interferon is specific in protecting primarily the cellular species in which it has been produced. For protecting human cells in vitro it is, therefore, important to employ an interferon produced by human cells. Accordingly, human leukocyte cells have been the most commonly used cells for the production of human interferon.
The therapeutic value of interferon has not been sufficiently explored because considerable difficulties have been encountered in mass production. For the large scale clinical trial required to sufficiently evaluate the therapeutic potential of human interferon, a more dependable and economical source than human luekocytes has been developed. This source is the lymphoblastoid cell (e.g., Namalva), a rapidly growing transformed lymphocyte capable of producing high titered interferon. Namalva interferon is similar to that produced by human leukocytes, thus providing a practical means of large scale production without relying on freshly harvested blood leukocytes. However, at present, Namalva cell interferon is produced in media containing calf serum proteins, making mandatory the removal of the extraneous animal blood proteins by extensive purification.
According to the present invention, the problem of contamination by non-human serum proteins is avoided. It has been found that human albumin can replace animal serum proteins for both the growth phase and the interferon production phase of Namalva cells.